Mathematics: The water works commission needs to know the mean household usage of water by the residents of a small town in gallons per day. they would like the estimate to have a maximum error of 0.15 gallons. a previous study found that for an average family the standard deviation is 2.3 gallons and the mean is 17.6 gallons per day. if they are using a 80% level of confidence, how large of a sample is required to estimate the mean usage of water? round your answer up to the next integer.

The water works commission needs to know the mean

jairus34

08.01.2022

387

Step-by-step explanation:

Given : Standard deviation: $\sigma=2.3$

Margin of error : 0.15

Critical value for 80% confidence interval = 1.2816

Required minimum sample size : $n=(\dfrac{z_{\alpha/2}\cdot \sigma}{E})^2$

$\\\\=(\dfrac{1.2816\times2.3}{0.15})^2\\\\=386.16966144\approx387$

Hence, the minimum sample size required to estimate the mean usage of water = 387

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ioifjifjie3054

28.11.2020

rate of change = -0.32

Step-by-step explanation:

Rate of change = slope,m

$m = \frac{y2 - y1}{x2 - x1} \\ m = \frac{3.6 - 2}{ - 3 - 2} \\ m = \frac{1.6}{ - 5} \\ m = \frac{ - 0.32}{1}$

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